exigence (n.)

mid-15c., "what is needed" (in a given situation), from Old French exigence or directly from Latin exigentia "urgency," from exigentem (nominative exigens), present participle of exigere "demand, require, enforce," literally "to drive or force out," also "to finish, measure," from ex "out" (see ex-) + agere "to set in motion, drive, drive forward; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move"). From 1580s as "state of being urgent."